Subject: DSI / LPI USB Power Levels Affecting Operation / Drivers Loading
Sent: Wednesday, February 23, 2005 07:05:40
From: Stephen Bird (stephen.bird@btconnect.com)
I noticed that there had been some concern over USB power levels, in
particular for the DSI and one person had noted the issue of powered and
non powered hubs. I had a play with both the LPI and DSI on my 3 PC's,
and noted that the LPI really does not care which port, USB1 or 2 is
used and whether a powered hub, non powered, or fixed port on the PC is
used.
The DSI is a different story. On some PC's with a number of integral USB
ports, if one or more other devices drawing power from the USB card are
connected (such as my DSL modem drawing 500mA), then the DSI is not
registered as being detected or gives an error message as the connection
is attempted by the Imaging software, (the error message is a long
series of computer gibberish about failed strings and the like). Worse
than that if you try to install the Autostar Suite and then the DSI, it
cannot see the DSI when you try to install the driver so the
installation fails. As I said the LPI loads just fine with my PC's on
the same USB ports so I assume it draws far less power.
Then with the same PC, but via a powered hub, the DSI loads its driver
and works fine every time. With Windows XP, two drivers are loaded for
the DSI, what you see is the driver part of the installation run twice,
one is the Meade DSI Driver, the other is something called EZ USB or
similar name.
And just to cause a little more surprise, if you remove all the power
sapping devices, or use a USB port on another discreet USB card in the
same PC, again the DSI will work just fine. I even have problems with
the front mounted port on a desktop, which is part of an array of ports
for USB, firewire and camera cards various. I can only think that this
port has a limited power supply that cannot power the DSI. The ports at
the back of this PC are fine, probably on a separate card with its own
supply internally??
So another suggestion for people having problems getting DSI (or LPI)
drivers to load, is to use a powered hub, and or, disconnect other USB
devices so that the DSI (or LPI) gets its full share of the USB power. I
have found that with XP, allowing this full availability of power gets
round the previous anomaly I saw of having to point the PC at the exact
location of the DSI / LPI drivers, I can now get them to consistently
load as per the Meade instructions every time. This does not work for my
Windows 2000 Laptop however, this still requires me to point the PC at
the location of the drivers on the hard disk when loading the Autostar
Suite for the first time.
Afraid I haven't been able to test this with Windows 98SE as I upgraded
that PC to XP when I got the DSI, but it might be worth someone trying
the USB powered hub to see if it helps those with problems on that
platform.
So to summarise, if you have driver of DSI operation problems, use a
powered hub, of disconnect other USB devices to see if that solves it.
If do then it could be a USB power problem.
Maybe Meade should state the power draw of the DSI and fit it with an
external supply connection for difficult situations.
Regards
Stephen Bird